Friday 28 May 2010 13.42 EDT
First published on Friday 28 May 2010 13.42 EDT

A feud between two London gangs, loosely emulating the "bloods" and "crips" of Los Angeles's territorial wars, is believed to be behind the shooting of an innocent man sunbathing in a London park.

Two bullets were fired during a clash near the perimeter of London Fields park in Hackney, north-east London, last Saturday. One penetrated the lower back of the 27-year-old man who had been sitting on the grass, leaving him with serious stomach injuries.

The park was packed with people enjoying the sunshine when a black Volkswagen vehicle and possibly a silver car pulled up on an adjacent road just before 3.30pm. A group of between five and eight youths wearing red bandanas – the mark of the "bloods" gang in Los Angeles – sprinted into the park and two shots rang out.

A moment later, the victim rolled over with blood running down his leg. He had been sitting about 100 metres from the road, where bullet casings were found. Sunbathers ran to his aid and asked him to stay calm. His injuries have been described as "life changing".

Naina Patel, 37, a physiotherapist who, with an accident and emergency nurse, gave the man medical attention before paramedics arrived, said the moment was "surreal". Patel said the man's girlfriend began shaking.

The man had been sitting having a drink and enjoying the park before the incident. "The sunniest day of the year, you go to enjoy it, and suddenly something as random as this happens," Patel said.

Amy, 27, a charity worker, said: "Everyone was looking beautiful in their trendy clothes. People were blowing bubbles and we had our guitars out."

Detectives from the Metropolitan police's Operation Trident gun crime unit arrested a 19-year-old man who was later released on bail.

Police are unsure what firearm was used but believe it may have been a converted starter pistol. A ban on the sale of such pistols, which can be bought for £90 over the internet, comes into force next week. The conversions have sometimes been crude, with weapons barely injuring their target or blowing up in the hands of those using them.

"In general terms, most firearms that are being used are converted starter pistols," said Chief Superintendent Steve Bending, Hackney's borough commander. "At the moment ammunition is reasonably scarce to get hold of, so sometimes even the ammunition is home-made. It means that those weapons are quite often inaccurate."

He appealed for witnesses and thanked more than 60 bystanders who have already come forward, some with mobile phone footage of the incident.

The shooting may reflect the division between two overlapping communities that co-exist in London but rarely mix. Few of the young professionals in the park would have known they were relaxing in what has become – particularly during the summer months – a borderland between rival east London gangs.

Jules Pipe, Hackney's mayor, suggested the shock and indignation at the shooting stemmed in part from the background of the victim, who is white. "You can almost grade the coverage and shock that society gives to these events," he said. "If a victim was a white, middle-class passer-by, it is when it would be on the front page of a tabloid."

Last month Agnes Sina-Inakoju, a 16-year-old black girl, was shot through her neck while standing in a Hackney take-away restaurant. Police believe she, too, was an unintended target.

Pipe said both shootings were "outrages", but added: "This is not Rio de Janeiro. There are not rows and rows of gentrified houses that are squeezing out a poor underclass that is rising up and engaging in drug dealing. I think that is just a million miles from the truth."

Community workers employed by the council to prevent teenagers from becoming sucked into the gangs say the problem is often exaggerated. There are more than 22,000 young teenagers in the borough, but only a tiny minority of about 10 are classed as "difficult and very dangerous".

Bending said gang disputes often revolved around territory. But feuds could similarly spiral from "trivial" issues to do with perceived loss of face, increasingly after postings on social networking sites, he added.

"It can be something about a Facebook comment. It can be around someone hearing a rumour that somebody has been hearing something about them. Then there is a perception of loss of face, that then results in retribution."

The notion that gangs are armed to the teeth is also misleading, he said. "Within a gang there is a concept of a pool gun. It is quite bizarre, but they will literally share a gun around. The important thing to realise is it doesn't always end up in people firing guns and stabbing people. That is the extreme."